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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: ingress SMTP
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Robert Bonomi wrote: > One small data-point -- on a personal vanity domain, approximately 2/3 of > all the spam (circa 15k junk emails/month) was 'direct to inbound MX' > transmissions. The vast majority of this is coming from end-user machines > outside of North America. This confirms the limited data I have. I configure my edge firewall (pf) to drop anything to/from the Spamhaus DROP list, as well as sendmail to use their XBL. The DROP list seems like it blocks mostly MX lookups (nice to see the blocking of mail start so early in the process!), so it is hard to say how many SMTP connections never happen (remote server/bot does not know where to connect). The XBL list, which is mostly residential IPs around the world, seems to be the single most effective technique in blocking incoming traffic-- on port 25. Obviously, these connections are coming from ISPs that do *not* block egress TCP 25. Slightly off topic-- I found it quite easy to configure the DROP list to work with pf (or is that the other way around?). I would be happy to share the small Perl script that updates the pf table. When I configured the DROP list on a free public wireless system I maintain, I was amazed at how much egress traffic it blocked-- obviously rogue/bad/evil webservers, IRC hosts, etc. I wonder if anyone else is using it that way? ... alec - -- `____________ / Alec Berry \______________________________ | Senior Partner and Director of Technology \ | PGP/GPG key 0xE8E9030F | | http://alec.restontech.com/#PGP | |-------------------------------------------| | RestonTech, Ltd. | | http://www.restontech.com/ | | Phone: (703) 234-2914 | \___________________________________________/ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIv+YdREO1P+jpAw8RAnWzAKDxOmneR6j6DBVyo5/CO1wRYngorQCgo9SJ sArBQqQStX7zIuYK3qo1El0= =C2FM -----END PGP SIGNATURE-----
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